下列微粒空间构型为平面三角形的是（ ） A．NF3 B．HCHO C．PCl

三. 任务型阅读
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Advantages and disadvantages of private cars
With the fantastic spur (刺激) both in industry and in economy in China, the number of people who own private cars is on the rise. Some people have bought cars of their own, and others are planning to buy cars. But there have been two quite different views on this phenomenon.
Some claim that there are many advantages brought about by cars. First, the automobile industry provides jobs for countless workers and strong support for other industries. Second, if conditions permit, owning a car can make us work more efficiently. Finally, life will become more convenient. A car allows one to move freely and with a car there is no need to wait for the bus in the cold or under the burning sun.
However, others strongly object to the increase in developing private cars. They hold that automobiles will give rise to a series of problems. In the first place, as more and more cars are produced and run in the street, a large volume of poisonous gas will be given off, polluting the atmosphere and causing actual harm to the health of people. Next, private cars contribute to traffic congestion (拥塞) so greatly that the advantages gained in comfort and freedom are often cancelled out by the frustration （挫折）caused by traffic jams. The last problem is the increasing number of car accidents that have killed and will kill a lot of people in a friction of a second.
In my opinion, although automobiles have been playing a vital part in the daily activities of our society, they also bring us numerous troubles such as more serious environmental pollution,  more traffic accidents and more energy consumption. They drink up huge amounts of fuel and throw out huge amounts of pollutants. Traffic accidents kill thousands and thousands of people each year and cripple more. Jams waste our precious time. Therefore I am against developing private cars.